FAMILY II. METHANOMONADACEAE 



77 



4. Hydrogenomonas vitrea Niklewski, 

 1910. (Jahrb. f. wissensch. Botanik, 48, 1910, 

 113.) 



vit're.a. L. vitreus of glass. 



Rods 2.0 microns in length, cells adhering 

 to each other as by slime. Motility not ob- 

 served. 



Agar colonies on inorganic medium in 

 presence of H2 , O2 and CO2 : Delicate, 

 transparent, with slight fluorescence and 

 yellow center. Surface folded. Do not de- 

 velop readily beneath the surface of me- 

 dium. 



Agar streak on inorganic substrate : Same 

 as agar colonies e.xcept that growth is 

 spreading. 



Inorganic liquid medium in presence of 

 H2 , O2 and CO2 : Pellicle, adherent to wall 



of tube. Good development when there is 

 from 2 to 8 per cent oxygen in the gas. At 

 higher O2 concentrations good growth occurs 

 only in association with H. flava or other 

 bacteria. 



Oxidizes hydrogen to water. 



Microaerophilic, growing in an atmos- 

 phere of low oxygen tension, not exceeding 

 8 per cent. 



Facultatively autotrophic. 



Distinctive characters: Grows in sub- 

 strates containing no organic matter and 

 produces a pellicle. 



Source: Isolated from mud, garden soil, 

 pasture land, vegetable mold and peat. 



Habitat: Presumably widely distributed 

 in soil. 



Gemis III. Carboxydonionas Orla-Jensen, 1909. 

 (Cent. f. Bakt., II Abt., 22, 1909, 311.) 



Car.box.y.do.mo'nas. L. noun carbo charcoal, carbon; Gr. adj. oxys sharp; Gr. noun 

 monas a unit, monad; M.L. fem.n. Carboxydomonas the carbon-oxidizing monad. 



Autotrophic, rod-shaped cells capable of securing growth energy by the oxidation of CO, 

 forming CO2 . 



The tj^pe species is Carboxydomonas oligocarbophila (Beijerinck and van Delden) Orla- 

 Jensen. 



1. Carboxydonionas oligocarbophila 



(Beijerinck and van Delden, 1903) Orla- 

 Jensen, 1909. (Bacillus oligocarbophilns 

 Beijerinck and van Delden, Cent. f. Bakt., 

 II Abt., 10, 1903, 33; Orla-Jensen, Cent. f. 

 Bakt., II Abt., 22, 1909, 311.)* 



o.li.go.car.bo'phi.la. Gr. adj. nligus 

 little, scanty; L. noun carbo charcoal, car- 

 bon; Gr. adj. ■philus loving; M.L. adj. oligo- 

 carbophilus loving little carbon. 



Rods very small, 0.5 by 1.0 micron, color- 

 less, united into irregular masses by a 

 slimy substance. Non-motile. There is little 

 cytoplasm within the slimy, cellulose-like 

 wall of the cells. 



Growth occurs in culture fluids free from 

 organic matter and on washed agar con- 

 taining the necessarj^ inorganic salts. 



Media containing carbonaceous materials : 

 No growth. 



Liquid media: A thick, slimy film is pro- 

 duced. 



CO is utilized as food and as such is oxi- 

 dized to CO 2 • In symbiosis with other bac- 

 teria, hj'drogen in water is o.xidized by the 

 catalytic reduction of CO2 to CO. The CO is 

 then metabolized, again forming CO2 (Ka- 

 serer. Cent. f. Bakt., II Abt., 16, 1906, 681). 



Growth best in the dark. 



Optimum temperature, 25° C. 



* Kistner (Proc. Kon. Nederl. Akad. van Wetenschappen, Amsterdam, Series C, 56, 

 1953, 443) , in a paper received after the section covering Carboxydomonas was prepared , ques- 

 tions the data gathered by Beijerinck, Kaserer, Lantzsch and others. He concluded that 

 their reports were based on doubtful and imperfect ol)servations. Using a carefully con- 

 trolled technique, he was able to isolate an organism which oxidized CO to CO2 and which 

 had the characters of a pseudomonad (polar flagellate, straight rod). On further testing, 

 however, because it also oxidized H2 , he concluded that it belonged in the genus Hydro- 

 genomonas. Further studies on the species are promised. 



